Fatigue and its impact on patients with myasthenia gravis.

We have examined fatigue in myasthenia gravis (MG) by administering a measure of cognitive and physical fatigue to patients and control subjects before and after administration of a lengthy cognitive battery. Subjects also completed a scale that assessed the impact of fatigue on physical, social, and cognitive function. Results of the study revealed that MG patients experience significantly more cognitive and physical fatigue than do control subjects, and the patients' perceptions of both cognitive and physical fatigue increased significantly following completion of demanding cognitive work. Control subjects reported no significant change in fatigue. Furthermore, MG patients reported that fatigue produced mild to moderate effects on cognitive and social function and moderate effects on physical function. Results from this study indicate that cognitive fatigue is an important symptom of MG and that fatigue produces pervasive impairments in important aspects of patients' lives. Additional studies are needed to understand the neurobehavioral determinants of cognitive fatigue in this population. Copyright 2000 John Wiley & Sons, Inc.